Gas burning wall heater



J1me 1966 K. L. BEDELL ETAL 3,258,004

GAS BURNING WALL HEATER Filed May 18, 1964 INVENTORJ KAEL 4. 550541. CHAELEF e H5405 ram/452, (M05155 GAMBEELL A T TOE/VE/Z mined change in the flue wall temperature occurs.

nitecl States Patent O 3,258,004 GAS BURNING WALL HEATER Karl L. Bedell, Pasadena, and Charles R. Fields, Arcadia, Calif, assignors to Williams Furnace (10., Buena Park, Calif., a corporation of Delaware Filed May 18, 1964, Ser. No. 368,062 3 Claims. (Cl. 126-110) This invention relates to gas burning heaters, and more particularly to improvements in the diverter and flue means employed to compensate for variations of the static pressure in the flue.

In the usual gas fired wall heater, the gas burners are enclosed by a heat exchanger hood which is connected to a flue for venting the combustion gases. Since gas heaters are designed to operate with optimum efliciency at a preselected static pressure in the heat exchanger hood and flue, such systems are sensitive to variations of the static pressure in the flue.

I order to desensitize gas burning heaters to variations of static pressure, it is conventional practice to connect a diverter box having a relief outlet to the flue above the heat exchanger hood. The diverter box does several things. If a down draft occurs or the flue is blocked by some obstruction, the flame will not be extinguished because the com'bustion gases will flow out into the room through the relief outlet. By the same token, extreme up-drafts, which can be caused by excessively high chimneys or can develop due to the presence of high winds, will suck air from the room into the flue in order to not interfere with the combustion process in the heat ex-. changer hood.

In cases of excessive up-draft, however, the relatively cool air pulled into the flue from the room normally mixes with the flue gases so that the combustion system will remain stable. This can substantially reduce the temperature of the flue walls, depending upon the magnitude of the up-drafts. In some wall heater designs, this type of overcompensation is deliberately used, not only to control the static pressure but to reduce the temperature of the flue walls as well. On the other hand, in other cases it is desirable to provide a diverter and flue arrangement which, in operation, does not change the temperature of at least a part of the flue wall even though excessive tip-drafts cause substantial quantities of fresh air to be sucked into the diverter box.

The present invention has particular application in gas burning wall heaters which utilize a thermally sensitive switch mounted on one wall of the flue to control a fan or other equipment. In such systems, the thermally sensitive switch is designed to operate when a predeter- The switch in operating may actuate a circulating fan, as it does in the illustrative embodiment herein, or it may control other devices to re-establish some other design parameter for the system.

When such switches are associated with a wall of the flue, it is important that the diverter box compensation system not materially lower the temperature of the wall to which the thermally sensitive switch is attached. Tests of actual'installation of appliances employing a thermally sensitive switch have shown that a temperature drop of approximately 25% will occur when an up-draft of approximately 0.15 inch negative pressure of H is present.

An object of this invention therefore, is to provide a system which blocks the flow of air from the flue into the heat exchanger hood and combustion chamber when a down draft occurs and, at the same time, prevents the compensatory air drawn in to stabilize excessive up-draft conditions from contacting the wall of the flue to which a thermally sensitive switch is attached.

Patented June 28, 1966 plate and arranged so that most of the relief air sucked into the diverter means to compensate for excessive updrafts flows through the rear chamber and most of the flue combustion gases flow through the front chamber.

In a more restricted sense, the present invention provides means to compensate for variations of the static pressure in the flue of a gas burning heater without materially cooling down a part of the front flue wall to which is attached a thermally sensitive switch. The invention combines a'flue for exhausting combustion gases, a heat exchanger hood disposed above the gas burners of the heater, a diverter chamber interconnecting the flue and the heat exchanger hood and in open communication with the flue and heat exchanger hood, a diverter box having a relief outlet disposed interior of the chamber at right angles to the flue and heat exchanger hood, and a splitter plate disposed interior of the lower part of the flue generally behind the front wall on which the thermally sensitive switch is mounted to divide the flue into front and rear chambers. The plate and diverter box are arranged so that the flue gases primarily flow around the sides of the diverter box and into the front chamber (which includes the front wall), and air drawn into the flue by way of the relief outlet of the diverter box flows generally through the rear chamber. The result is that flue gases and relief air do not intermix until they are substantially above the s ction of the flue upon which the thermally sensitive switch is mounted. With this construction, it is possible to maintain the static pressures in the heat exchanger hood without adversely affecting the temperature of the front flue wall.

These and other objects and features of the present invention may be more fully understood when the following detailed description is read in reference to the drawings in which:

FIG.l is a side section view of an exemplary gas burning wall heater utilizing the present invention;

FIG. 2 is a top section view of the diverter chamber and box and flue taken along line 22 of FIG. 1;

FIG. 3 is a section view taken along line 33 of FIG. 1; and

FIG. 4 is a partial rear perspective of the diverter chamber and diverter box showing the construction of the diverter box.

Looking to the figures, the exemplary wall heater 10 includes a rectangularly-shaped elongated outer shell 11 having upper and lower grilles 13 and 14 in its front wall and a plurality of gas burners 16 attached to a cross plate in its lower end. The burners 16 are supplied gas fromv a source (not shown) and can be lighted and adjusted by automatic means 17. system can be any kind conventionally used in gas heaters.

The burners 16 have a primary heat exchanger hood 21 disposed thereover. The primary hood 21 is reduced in cross-section at its upper end to connect to the secondary heat exchanger hood 22. The upper heat exchanger hood 22 is of a flat rectangular shape and is connected to the bottom of the generally rectangularly-shaped diverter chamber 26. The diverter chamber 26 surrounds diverter box 27.

The flue 31 is offset horizontally from the upper hood 22 and is attached to the rear wall of the diverter chamber The burners and ignition 3 26, but it is in open communication with the diverter chamber 26, the heat exchanger hoods 22 and 21.

The rear wall 32 of the diverter chamber 26 defines a circular aperture 33 between the flue 31 and the chamber 26 (see FIG. 3, particularly). A splitter plate 36 is supported in the lower part of flue 31 with its lower end 37 terminating approximately at the midpoint of the circular aperture 33. Plate 36 extends between the sides of flue 31 to form a front chamber 38 and a rear chamber 39 in the lower part of the flue 31.

The diverter chamber 26 has an outer trapezoidalshaped hood or open box 41 affixed to its forward edge which terminates adjacent the front wall of the heater 11 in immediate juxtaposition to the air inlet grill 13. The diverter box 27 has roughly a square cross-section at its point of attachment to the apertured front wall of chamber 26 (at the start of hood 41). It includes a pair of parallel side baflle plates 42, a bottom or lower battle plate 43 which extends toward the rear wall of the heater 11 in an upwardly direction, and a relatively short top or upper baffle plate 44 bridging the parallel sides 42.

The lower baffle 43 extends substantially across the diverter chamber 26, bridging it from front to rear. However, its width is not as great as the diverter chamber 26. This can be seen most clearly in FIG. 2.

In operation, the combustion gases from the primary heat exchanger hood 21 move through the secondary heat exchanger hood 22, which has a corrugated-type crosssection to disperse the gases along the full width thereof, and into the lower part of the chamber 26. Under normal operating conditions, these combustion gases, represented by the dotted arrows, are diverted by the baffle plate 43 of the diverter box 27 and flow around the side baflie plates 42 (see FIG. 3). From the upper part of chamber 26, the flue gases flow into the front chamber 38 of the flue 31.

Whenever an excessive up-draft occurs, air is drawn through the diverter box 27 from the room (represented by the solid arrows) and, because the air is relatively cool, it moves toward the lower part of aperture 33 and mostly up through the rear chamber 39 formed by the splitter plate 36 and the back wallof the flue 31. Even though relief air is drawn through the diverter box 27, the combustion gases continue to pass around the diverter box 27 and, because they are at a relatively high tempera- Y ture, through the upper part of aperture 33 and into the front chamber 38 formed by the splitter plate 36 and the front wall of the flue 31.

Whenever a down draft occurs with the present construction, air moving down the flue 31 encounters the baffles forming the diverter box 27. This prevents the down draft from extinguishing the flames in the burners. Yet, the air can still flow out of the diverter box 27 into the room as a safety precaution.

This arrangement substantially prevents the flue gases and relief air from mixing until they reach a point in the flue 31 substantially above the diverter chamber 26, a point in fact defined by the upper edge 50 of the splitter plate 36.

If the thermally sensitive switch 51 is mounted on the front wall of the flue 31 below the upper edge 50 of the splitter plate 36, it will be relatively unaffected by relief air sucked into the diverter box 27 to maintain optimum combustion conditions in the heat exchanger hoods 21, 22.

In the exemplary embodiment of the present invention, a circulating fan 56 is provided adjacent the incoming air vent 13 to pull air into the heater and flow it out of the exhaust grill 14 after it absorbs heat from the surfaces of hoods 21 and 22. This fan could be operated, for example, by the thermally sensitive switch 51 whenever the temperature of the flue wall reached a certain value. Irrespective of the use made of the output of the switch 51, it can be appreciated that such switches must operate relatively independently of the up-drafts or down-drafts. Otherwise, over-heating of appliances or ineflicient operation of the heating system depending upon the proper operation of the switch will result.

While this invention has been described with reference to a preferred embodiment, it should be apparent to those skilled in the art that various changes can be envisioned which do not depart from the spirit and scope of the invention. For this reason, the invention should be limited only to the extent of the appended claims.

What is claimed is:

1. In a gas burning heater having diverter means between the combustion chamber and flue to permit outside air to be introduced to protect the gas combustion process from extreme up-drafts ordown drafts, the combination of a thermally-sensitive switch mounted on one external wall of said flue and operative to provide a control output;

means disposed interior of said diverter means to keep the flue gases and relief air substantially separated; and

means, associated with said flue to direct most of said flue gases along said one wall and most of said relief air along other walls until the part of said flue upon which said switch is mounted is traversed.

2. In a gas burning heater having a thermally sensitive switch mounted on the front wall of the lower part of the flue to provide a control output, a flue gas and relief air system designed to operate without materially changing the temperature of the front wall of the flue upon which the thermally senstive switch is located comprising, in combination,

a hood having a diverter chamber connected at its upper end;

a flue attached to the back of said diverter chamber offset from said hood;

said hood, diverter chamber and flue in open communication with each other;

a splitter plate supported in the lower part of said flue adjacent said diverter chamber and behind the front wall on which is mounted the thermally sensitive switch;

said plate dividing the lower part of said flue into front and rear chambers; and

an open-ended diverter box having a relief air inlet disposed in said diverter chamber with the lower side thereof substantially bridging said diverter chamber from front to rear so that the flue gas flows around said diverter box and into said front chamber and relief air introduced to compensate for severe tip-drafts flows through said diverter box and into said rear chamber;

said flue gas and relief air only mixing in the flue above the upper edge of said splitter plate.

3. A flue gas and relief air system in accordance with claim 2 wherein the lower edge of said splitter plate terminates toward the middle of the opening between said flue and said diverter chamber.

References Cited by the Examiner UNITED STATES PATENTS 2,888,911 6/1959 Thompson 126--307 X FOREIGN PATENTS 284,024 11/ 1952 Switzerland.

FREDERICK KETTERER, Primary Examiner. 

2. IN A GAS BURNING HEATER HAVING A THERMALLY SENSITIVE SWITCH MOUNTED ON THE FRONT WALL OF THE LOWER PART OF THE FLUE TO PROVIDE A CONTROL OUTPUT, A FLUE GAS AND RELIEF AIR SYSTEM DESIGNED TO OPERATE WITHOUT MATERIALLY CHANGING THE TEMPERATURE OF THE FRONT WALL OF THE FLUE UPON WHICH THE THERMALLY SENSITIVE SWITCH IS LOCATED COMPRISING, IN COMBINATION, A HOOD HAVING A DIVERTER CHAMBER CONNECTED AT ITS UPPER END: A FLUE ATTACHED TO THE BACK OF SAID DIVERTER CHAMBER OFFSET FROM SAID HOOD; SAID HOOD, DIVERTER CHAMBER AND FLUE IN OPEN COMMUNICATION WITH EACH OTHER; A SPLITTER PLATE SUPPORTED IN THE LOWER PART OF SAID FLUE ADJACENT SAID DIVERTER CHAMBER AND BEHIND THE FRONT WALL ON WHICH IS MOUNTED THE THERMALLY SENSITIVE SWITCH; SAID PLATE DIVIDING THE LOWER PART OF SAID FLUE INTO THE FRONT AND REAR CHAMBERS; AND AN OPEN-ENDED DIVERTER BOX HAVING A RELIEF AIR INLET DISPOSED IN SAID DIVERTER CHAMBER WITH THE LOWER SIDE THEREOF SUBSTANTIALLY BRIDGING SAID DIVERTER CHAMBER FROM FRONT TO REAR SO THAT THE FLUE GAS FLOWS AROUND SAID DIVERTER BOX AND INTO SAID FRONT CHAMBER AND RELIEF AIR INTRODUCED TO COMPENSATE FOR SEVERE UP-DRAFTS FLOWS THROUGH SAID DIVERTER BOX AND INTO SAID REAR CHAMBER; SAID FLUE GAS RELIEF AIR ONLY MIXING IN THE FLUE ABOVE THE UPPER EDGE OF SAID SPLINTER PLATE. 